Catalyst Engineering for the Selective Reduction of CO to CH : A First-Principles Study on X-MOF-74 (X=Mg, Mn, Fe, Co, Ni, Cu, Zn).

The conversion of carbon dioxide (CO ) into more valuable chemical compounds represents a critical objective for addressing environmental challenges and advancing sustainable energy sources. The CO reduction reaction (CO RR) holds promise for transforming CO into versatile feedstock materials and fuels. Leveraging first-principles methodologies provides a robust approach to evaluate catalysts and steer experimental efforts. In this study, we examine the CO RR process using a diverse array of representative cluster models derived from X-MOF-74 (where X encompasses Mg, Mn, Fe, Co, Ni, Cu, or Zn) through first-principles methods. Notably, our investigation highlights the Fe-MOF-74 cluster's unique attributes, including favorable CO binding and the lowest limiting potential of the studied clusters for converting CO to methane (CH ) at 0.32 eV. Our analysis identified critical factors driving the selective CO RR pathway, enabling the formation CH on the Fe-MOF-74 cluster. These factors involve less favorable reduction of hydrogen to H and strong binding affinities between the Fe open-metal site and reduction intermediates, effectively curtailing desorption processes of closed-shell intermediates such as formic acid (HCOOH), formaldehyde (CH O), and methanol (CH OH), to lead to selective CH formation.